The synthesis of natural products (e.g., eriolanin, eriolangin, helenalin, elephantopin, bruceantin) and analogs (6-epi-eriolangin, deoxyelephantopin, deoxyvernolepin, A-norbruceantin (138)) which are known to possess structural featues (alpha, Beta-unsaturated carbonyls) responsible for the tumor inhibitory activities are planned. The development of new methods of organoselenium chemistry for application to the syntheses of the above named natural products and analogs will be undertaken. The various compounds synthesized will permit in vivo testing as well as allow further structure-activity relationship studies to continue. It is hoped that the various substrates encountered during this study will exhibit selective toxicity against neoplastic cells to be of chemotherapeutic value.